In order to be able to solve the xray puzzle once you’ve turned the power on, you need to find the 2 slides to add to the light box. One is in the Quarantine Room and one is in the Laboratory.
If your game does not position the slides the way mine did, you can compare the two slides of the left hemisphere and take the one that is smaller and then compare the two slides of the right hemisphere and take the one that is smaller.
First, add #2, which is the one piece that has both sides on it. That one goes at the bottom. Then I added #1, which is the left hemisphere. Then i added #4. Align them so the skull border lines up. The slides will overlap. That’s ok.
Once you have the skull border aligned, the game will autocomplete it for you.